anisomycin and benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone

Mitotic catastrophe (MC) is induced when stressed cells enter prematurely or inappropriately into mitosis and can be caused by ionizing radiation and anticancer drugs. Foretinib is a multikinase inhibitor whose mechanism of action is incompletely understood. We investigated here the effect of Foretinib on chronic myelogenous leukemia (CML) cell lines either sensitive (IM-S) or resistant (IM-R) to the tyrosine kinase inhibitor Imatinib. Foretinib decreased viability and clonogenic potential of IM-S and IM-R CML cells as well. Foretinib-treated cells exhibited increased size, spindle assembly checkpoint anomalies and enhanced ploidy that collectively evoked mitotic catastrophe (MC). Accordingly, Foretinib-stimulated CML cells displayed decreased expression of Cdk1, Cyclin B1 and Plk1. In addition, Foretinib triggered caspase-2 activation that precedes mitochondrial membrane permeabilization. Accordingly, z-VAD-fmk and a caspase-2 siRNA abolished Foretinib-mediated cell death but failed to affect MC, indicating that Foretinib-mediated apoptosis and MC are two independent events. Anisomycin, a JNK activator, impaired Foretinib-induced MC and inhibition or knockdown of JNK phenotyped its effect on MC. Moreover, we found that Foretinib acted as a potent inhibitor of JNK. Importantly, Foretinib exhibited no or very little effect on normal peripheral blood mononuclear cells, monocytes or melanocytes cells but efficiently inhibited the clonogenic potential of CD34+ cell from CML patients. Collectively, our data show that the multikinase inhibitor Foretinib induces MC in CML cells and other cell lines via JNK-dependent inhibition of Plk1 expression and triggered apoptosis by a caspase 2-mediated mechanism. This unusual mechanism of action may have important implications for the treatment of cancer.

Topics: Amino Acid Chloromethyl Ketones; Anilides; Anisomycin; Antigens, CD34; Antineoplastic Agents; Benzamides; Caspase 2; Caspase Inhibitors; CDC2 Protein Kinase; Cell Cycle Proteins; Cell Death; Cell Size; Cell Survival; Cyclin B1; Cysteine Endopeptidases; Enzyme Activation; Enzyme Assays; Humans; Imatinib Mesylate; K562 Cells; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Leukocytes, Mononuclear; M Phase Cell Cycle Checkpoints; MAP Kinase Signaling System; Melanocytes; Mitosis; Phenotype; Piperazines; Ploidies; Polo-Like Kinase 1; Protein Kinase Inhibitors; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Pyrimidines; Quinolines; RNA, Small Interfering; Transfection

Ovarian surface epithelial cells (OSEs), a single layer of cells that cover the surface of the ovary, undergo turnover at the site of follicular rupture at ovulation. Greater than 90% of ovarian cancers arise from the OSEs. The objective of this study was to determine whether OSEs have the capacity to regulate their own demise through expression of Fas antigen (Fas) and Fas ligand (FasL) and activation of Fas-mediated apoptosis. In initial experiments, primary cultures of bovine OSEs responded to treatment with recombinant FasL by undergoing apoptosis. The percentage of cell death was not affected by the presence or absence of serum in the media or by co-treatment with interferon-gamma, a treatment shown to potentiate Fas-mediated apoptosis in a number of cell types. Subsequent experiments tested the ability of stress-inducing drugs, anisomycin and daunorubicin, to promote apoptosis by stimulating an endogenous Fas-FasL pathway in OSEs. Treatment with FasL, anisomycin or daunorubicin induced cell death and this was suppressed by co-treatment with a peptide inhibitor of caspases, ZVAD. Treatment with anisomycin or daunorubicin in the presence of ZVAD increased expression of FasL mRNA and protein but did not alter expression of Fas mRNA or protein. Treatment of OSEs with a recombinant protein that blocks interaction of FasL with Fas (Fas:Fc) reduced apoptosis in response to anisomycin and daunorubicin, indicating that drug-induced apoptosis was mediated at least partially through endogenous Fas-FasL interactions. In summary, OSEs undergo apoptosis in response to stress-inducing drugs through activation of an endogenous Fas pathway.

Topics: Amino Acid Chloromethyl Ketones; Animals; Anisomycin; Apoptosis; Caspase Inhibitors; Cattle; Cell Survival; Cells, Cultured; Daunorubicin; Epithelial Cells; Fas Ligand Protein; fas Receptor; Female; Membrane Glycoproteins; Ovary; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; Staining and Labeling; Tumor Necrosis Factors

During many forms of apoptosis, Bax, a pro-apoptotic protein of the Bcl-2 family, translocates from the cytosol to the mitochondria and induces cytochrome c release, followed by caspase activation and DNA degradation. Both Bcl-X(L) and the protein phosphatase inhibitor calyculin A have been shown to prevent apoptosis, and here we investigated their impact on Bax translocation. ML-1 cells incubated with either anisomycin or staurosporine exhibited Bax translocation, cytochrome c release, caspase 8 activation, and Bid cleavage; only the latter two events were caspase-dependent, confirming that they are consequences in this apoptotic pathway. Both Bcl-X(L) and calyculin A prevented Bax translocation and cytochrome c release. Bcl-X(L) is generally thought to heterodimerize with Bax to prevent cytochrome c release and yet they remain in different cellular compartments, suggesting that their heterodimerization at the mitochondria is not the primary mechanism of Bcl-X(L)-mediated protection. Using chemical cross-linking agents, Bax appeared to exist as a monomer in undamaged cells. Upon induction of apoptosis, Bax formed homo-oligomers in the mitochondrial fraction with no evidence for cross-linking to Bcl-2 or Bcl-X(L). Considering that both Bcl-X(L) and calyculin A inhibit Bax translocation, we propose that Bcl-X(L) may regulate Bax translocation through modulation of protein phosphatase or kinase signaling.

Topics: Amino Acid Chloromethyl Ketones; Anisomycin; Apoptosis; bcl-2-Associated X Protein; bcl-X Protein; BH3 Interacting Domain Death Agonist Protein; Biological Transport; Carrier Proteins; Caspase 8; Caspase 9; Caspases; Cysteine Proteinase Inhibitors; Cytochrome c Group; Cytosol; HL-60 Cells; Humans; Marine Toxins; Mitochondria; Oxazoles; Protein Synthesis Inhibitors; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2

Apoptosis, a physiological form of cell death, is characterized by the activation of a program that kills cells and recycles their constituents. We have used thymoma cell lines to examine the role of Bcl-2 and caspases in ribosomal destruction during apoptosis. Glucocorticoid- and calcium ionophore (A23187)-induced apoptosis of S49 Neo cells resulted in both 28S rRNA and DNA degradation. Interestingly, anisomycin, a potent protein synthesis inhibitor, also induced 28S rRNA and DNA fragmentation suggesting that the responsible nucleases are present in the viable cells and become activated during apoptosis. The anti-apoptotic protein, Bcl-2, inhibited both glucocorticoid- and anisomycin-induced DNA and 28S rRNA degradation but could not protect against A23187-induced nucleic acid degradation. We next examined the role of caspase activation in the generation of 28S rRNA degradation through the use of ZVAD, a general caspase inhibitor. Under conditions where ZVAD substantially decreased 28S rRNA degradation induced by glucocorticoid or anisomycin, no decrease was observed when A23187 was used to induce apoptosis. Surprisingly, RNA degradation, like DNA degradation, occurs exclusively in shrunken lymphocytes but not those with normal cell volume despite equivalent exposure of the cells to the apoptotic signals. Together, these findings indicate the ribosome is a specific target for death effectors during apoptosis and that a caspase/Bcl-2-independent pathway exists to activate its destruction.

Topics: Amino Acid Chloromethyl Ketones; Animals; Anisomycin; Apoptosis; Blotting, Northern; Caspases; Cysteine Proteinase Inhibitors; DNA, Neoplasm; Lymphocytes; Mice; Protein Synthesis Inhibitors; Proto-Oncogene Proteins c-bcl-2; RNA, Messenger; RNA, Ribosomal, 28S; Thymoma; Tumor Cells, Cultured